SnO2/TiO2 nanocomposites are fabricated by depositing amorphous SnO2 and TiO2 films alternately using pulsed laser deposition (PLD) system. The prepared nanocomposite anode delivers a high reversible capacity of 175 μA h cm−2 at 13.8 μA cm−2 after 200 cycles, and exhibits high rate capability (111 μA h cm−2 at 276 μA cm−2). Additionally, a quasi-solid-state battery is also assembled by using the granular film as a self-supporting electrode material, which displays superior cycling stability (136 μA h cm−2 at 13.8 μA cm−2 after 200 cycles). The excellent performance of the SnO2/TiO2 multilayer anodes can be attributed to the multilayer heterogeneous structure and component. In such a granular film structure, the amorphous structure can not only buffer stress, but also promote the diffusion of Li ions. Furthermore, the TiO2 layers can limit the volume expansion of SnO2 layer, and the densely packed film structure can avoid aggregation of the nanoparticles and assure structural integrity. Our SnO2/TiO2 nanocomposite, taking advantage of the high specific capacity of SnO2 and the long cycle life of TiO2, has potential applications in high performance LIBs, especially in thin-film microbatteries and flexible lithium batteries.
Different antibiotics are used to treat mastitis in dairy cows that is caused by Escherichia coli (E. coli). Antimicrobial resistance in food-producing animals in China has been monitored since 2000. Surveillance data have shown that the prevalence of multiresistant E. coli in animals has increased significantly. This study aimed to investigate the occurrence and molecular characteristics of resistance determinants in E. coli strains (n = 105) obtained from lactating cows with clinical bovine mastitis (CBM) in China. A total of 220 cows with clinical mastitis, which has swollen mammary udder with reduced and red or gangrenous milk, were selected from 5000 cows. The results showed 94.3% of the isolates were recognized as multidrug resistant. The isolates (30.5%) were positive for the class I integrase gene along with seven gene cassettes that were accountable for resistance to trimethoprim resistance (dfrA17, dfr2d and dfrA1), aminoglycosides resistance (aadA1 and aadA5) and chloramphenicol resistance (catB3 and catB2), respectively. The blaTEM gene was present in all the isolates, and these carried the blaCTX gene. A double mutation in gyrA (i.e., Ser83Leu and Asp87Asn) was observed in all fluoroquinolone-resistant isolates. In total, nine fluoroquinolone-resistant E. coli isolates were identified with five different types of mutations in parC. In four (44.4%) isolates, Ser458Ala was present in parE, and in all nine (9/9) fluoroquinolone-resistant isolates, Pro385Ala was present in gyrB. Meanwhile, fluoroquinolone was observed as highly resistant, especially in isolates with gyrA and parC mutations. In summary, the findings of this research recognize the fluoroquinolone resistance mechanism and disclose integron prevalence and ESBLs in E. coli isolates from lactating cattle with CBM.
Layered metal oxide cathodes suffer from a low specific capacity (below 200 mAh g–1), while long-term capacity retention is limited by electrolyte decomposition at high voltage (>4.5 V), decohesion, and fracture in primary grains upon cycling. Here, LiNi0.5Co0.2Mn0.3O2 (NCM523) at 4.8 V, employing p-toluenesulfonyl isocyanate (PTSI) as an electrolyte additive, has been investigated, which shows much improved cycling capabilities and rate performances for long-term cycling when a cell voltage of 4.8 V is applied. On the basis of the electrochemical analysis results and the first-principles calculation, the product CH3C6H4NCO from PTSI can be polymerized to produce a polymer (CH3C6H4NCO)2 to generate a stable solid electrolyte interphase film on the NCM523 cathode, which inhibits the decomposition of the electrolyte upon cycling at 4.8 V and offers a long-term cycling performance over 680 cycles. This work emphasizes that in situ surface protection induced by electrolyte additives can drive stable cycling of layered metal oxide cathodes at 4.8 V in advanced Li-ion batteries.
The quantitative measurement of cancer biomarkers based on aptamer-protein binding plays an important role in early cancer diagnosis. Conventional aptamer-based optical biosensing utilizes gold nanoparticles for aptamer modification. The use of iron nanoparticles can simplify the detection procedure due to its magnetic response. Here, we explore the use of ferrotetroxide nanoparticles for the modification of MUC-1-targeting aptamers. Mixtures with aptamer concentration ranging from 0 nM to 1000 nM were measured on a previously reported metamaterial structure. The results suggest that ferrotetroxide nanoparticles can successfully bind with aptamers with enhanced sensitivity in the terahertz frequencies.
Unidirectional propagation based on surface magnetoplasmons (SMPs) has recently been realized at the interface of magnetized semiconductors. However, usually SMPs lose their unidirectionality due to non-local effects, especially in the lower trivial bandgap of such structures. More recently, a truly unidirectional SMP (USMP) has been demonstrated in the upper topological non-trivial bandgap, but it supports only a single USMP, limiting its functionality. In this work, we present a fundamental physical model for multiple, robust, truly topological USMP modes at terahertz (THz) frequencies, realized in a semiconductor-dielectric-semiconductor (SDS) slab waveguide under opposing external magnetic fields. We analytically derive the dispersion properties of the SMPs and perform numerical analysis in both local and non-local models. Our results show that the SDS waveguide supports two truly (even and odd) USMP modes in the upper topological non-trivial bandgap. Exploiting these two modes, we demonstrate unidirectional SMP multimode interference (USMMI), being highly robust and immune to backscattering, overcoming the back-reflection issue in conventional bidirectional waveguides. To demonstrate the usefullness of this approach, we numerically realize a frequency- and magnetically-tunable arbitrary-ratio splitter based on this robust USMMI, enabling multimode conversion. We, further, identify a unique index-near-zero (INZ) odd USMP mode in the SDS waveguide, distinct from conventional semiconductor-dielectric-metal waveguides. Leveraging this INZ mode, we achieve phase modulation with a phase shift from -$\pi$ to $\pi$. Our work expands the manipulation of topological waves and enriches the field of truly non-reciprocal topological physics for practical device applications.
To develop effective insecticides against Lepidoptera pests, 25 novel N-pyridylpyrazole derivatives containing thiazole moiety were designed and synthesized based on the intermediate derivatization method (IDM). The insecticidal activities of these target compounds against Plutella xylostella (P. xylostella), Spodoptera exigua (S. exigua), and Spodoptera frugiperda (S. frugiperda) were evaluated. Bioassays indicated that compound 7g−7j exhibited good insecticidal activities. Compound 7g showed especially excellent insecticidal activities against P. xylostella, S. exigua, and S. frugiperda with LC50 values of 5.32 mg/L, 6.75 mg/L, and 7.64 mg/L, respectively, which were adequate for that of commercial insecticide indoxacarb. A preliminary structure-activity relationship analysis showed that the insecticidal activities of thiazole amides were better than that of thiazole esters, and the amides with electron-withdrawing groups on the benzene ring were better than the ones with electron-donating groups. This work provides important information for designing novel N-pyridylpyrazole thiazole candidate compounds and suggests that the 7g is a promising insecticide lead for further studies.
We developed a GaAs Schottky diode with integrated periodic subwavelength metal microslits with total internal reflection (TIR) geometry to achieve deep broadband THz modulation at high frequency with low insertion loss. The non-resonant electric field enhancement effect in the subwavelength microslits intensifies the evanescent wave in TIR, which increases broadband absorbance of THz light signals by free carriers in the GaAs Schottky diode. Devices with various microslit spatial periods and gap widths were fabricated and measured. Among the devices, that with a microslit period of 10 µm and gap width of 2 µm produced ∼70% modulation depth at frequencies of 0.2 to 1.2 THz, while in the range of 0.25 to 0.4 THz, ∼90% modulation depth was achieved. By encapsulating the device in high refractive index material, ∼100% modulation depth was achieved in the range of 0.4 to 0.6 THz, the 3 dB bandwidth operational frequency was ∼160 kHz, and the insertion loss introduced by the device was less than 8 dB, which is much lower than existing metasurface-based THz modulators. In general, our first-generation device has improved modulation depth, operational bandwidth, insertion loss, and operational frequency. Optimization of the metal microslits, TIR geometry, and doped layer could further improve the performance of our design.
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